Will this rig get me thru the western mountains

I have the smaller 310 HP engine on my 32 feet long, always pull a Toad and have not been stopped by a mountain yet. You will have no problems, you will not be the first to the top on some but none will stop you. Speed is what will kill you on milage you are driving a brick through the wind. My mileage is usually 8mpg to 8.5 mpg staying under 65 mph. Over 65 mph mileage will drop. Mine has 127,000 plus miles and been in all the western states and over just about all the passes. Go for it.